1. Field of the Invention
This invention relates to high throughput cup wheel superfinishing systems and methods therefore, in particular relating to workpiece identification, loading, unloading and repositioning.
2. Description of the Prior Art
Superfinishing is a well known process in which an outer surface of a workpiece is removed, using a process which generates little heat or surface stress, to produce a smooth surface having a precise contour and properties similar to the bulk material.
A superfinishing operation can be performed on almost any previously machined surface which may have a flat, cylindrical, spherical or other specific configuration. It improves the finish of the previously machined surface by removing surface material or “smear metal” left by the previous machining operation, and by cutting off ridges on the base metal surface of the workpiece. Superfinishing can also effect small corrections in the dimensions or shape of the workpiece. A superfinished surface is also characterized by a pattern of minute scratch marks which are beneficial for purposes of lubrication. Such scratch marks may take the form of a cross-hatched pattern cut by a combination of workpiece and stone movements.
Known processes employ, for example, a fine abrasive cup wheel to produce an abrasive pattern having a relatively constant relative velocity, which due to the rotation of the cup and workpiece, acts on the surface at in an area contact at nearly right angles, producing the characteristic cross hatch surface pattern. The process is typically controlled to apply a constant force on the workpiece surface, with the cup wheel spinning rapidly and the workpiece moving slowly, so that the cup wheel provides a treatment to all regions of the surface at least once (and in general, many times). This arrangement is useful for finishing planar or spherical surfaces.
A conventional superfinishing stone is formed as a block of solid abrasive material and relies on a coolant, commonly of relatively high viscosity, flooded over the stone and workpiece surface by means of external supply nozzles or by immersion. Such conventional stones are specially compounded to the user's specifications as to size, grit material, bond and hardness.
Typically, a superfinishing operation is controlled based on a pressure of the abrasive on the workpiece. This provides uniformity of treatment over corresponding parts of respective workpieces, and to the extent topological issues are resolved, globally uniform treatment, regardless of original surface configuration. This, in turn, requires a close loop servo feedback control system, to position the workpiece and abrasive in accordance with their relative force.